Patient education: Clotting factor blood test (The Basics)

What are clotting factors? — These are natural proteins found in the blood. They help the blood to clot. This is important so that the body can control bleeding if you get a cut or injury. Doctors also use the term "coagulation factors."

The body makes many different clotting factors. Some of them have names like "fibrinogen" and "prothrombin." Some of them are named with Roman numerals. For example:

●"Factor VIII" is missing or very low in people with hemophilia A.

●"Factor IX" is missing or very low in people with hemophilia B.

When certain clotting factors are missing or too low, this can cause dangerous bleeding.

A blood test can check 1 or more of your clotting factors.

What is a clotting factor test? — This is a blood test to measure 1 of your clotting factors and check how well it is working. It can show if the clotting factor is not working correctly because it is missing or too low.

Less commonly, there might be enough of the factor, but it is not working as it should.

Why might I get a clotting factor test? — Doctors can do a clotting factor test:

●If you had a general blood clotting test, like a "PT/INR" or "PTT," and the results were abnormal – The PT and PTT tests measure how long it takes your blood to clot.

●If a bleeding disorder like hemophilia runs in your family

●If the doctor suspects that your body is making antibodies against 1 of your own clotting factors

●To monitor you if you are getting treatment for a bleeding disorder like hemophilia

How do I prepare for a clotting factor test? — For this test, you need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

What happens during a blood draw? — For the blood draw, a needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in. Hold pressure on the area and make sure that the bleeding stops before you leave.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

If the test shows that your clotting factor is low, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out the cause.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.

More on this topic

Patient education: Prothrombin time and INR (PT/INR) (The Basics)
Patient education: Partial thromboplastin time test (The Basics)
Patient education: Hemophilia (The Basics)
Patient education: von Willebrand disease (The Basics)
Patient education: Disseminated intravascular coagulation (The Basics)
Patient education: Managing increased bleeding risk (The Basics)

Patient education: von Willebrand disease (Beyond the Basics)